Crimping rolls for thermoplastic materials

ABSTRACT

Crimping rolls for crimping thermoplastic textile material are provided with inclined engravings on the customary heated roll, with the engravings inclined in one direction on part of the roll and the opposite direction on the other, forming inverted or upright V&#39;&#39;s. The embossed roll, which is embossed by running against the engraved roll, similarly has its embossing inclined in more than one direction. Preferably, the embossed roll may be provided with a central rigid spacer or several if the rolls are divided into four instead of two parts. The inclined engravings and mating embossings do not cause the surface of the embossed roll, which is usually a non-woven hard felt surface, to creep in a single direction, and wear is reduced and frequency of having to true-up the embossed roll is greatly reduced.

United States Patent Yarber (TRIMIING ROLLS FOR 'IHERMOPLAQTIC MATERIALS Inventor: Harold Dean Yarben -Wallaee, N.C.

Assignee: J. P. Stevens & Co., Inc,, New York,

Filed: June 17, 1971 Appl. No.: 154,109

References Cited UN lTED STATES PATENTS Hollman ..26/D1G. 1

Mellor et a1. ..26/69 R Mahoney et a1. ..26/63 X FOREIGN PATENTS OR APPLICATIONS 8/1906 Germany ..26/69 R Hollihan et a1. ..28/1.8

Feb. 6, 1973 [57 ABSTRACT Crimping rolls for crimping thermoplastic textile material are provided with inclined engravings on the customary heated roll, with the engravings inclined in one direction on part of the roll and the opposite direction on the other, forming inverted or upright Vs. The embossed roll, which is embossed by running against the engraved roll, similarly has its embossing inclined in more than one direction. Preferably, the embossed roll may be provided with a central rigid spacer or several if the rolls are divided into four instead of two parts. The inclined engravings and mating embossings do not cause the surface of the embossed roll, which is usually a non-woven hard felt surface, to creep in a single direction, and wear is reduced and frequency of having to true-up the embossed roll is greatly reduced.

6 Claims, 1 Drawing Figure PATENIEDFEB 6191s 7 3,714,685

I INVENTOR. HAROLD DEAN YARBER ATTORNEY CRIMPING ROLLS FOR THERMOPLASTIC MATERIALS BACKGROUND OF THE INVENTION Crimping of thermoplastic textile materials, such as yarns made of materials which are thermoplastic, for example nylon, acrylics, polyolefins and the like, is effected by passing between a pair of rolls, one of them being a metal roll engraved with the engraving lines 1 slanting in one direction and the roll being heated by steam or other means and an embossed roll which is pressed against the engraved roll and normally made up of a series of rings of chopped wool or wool and cotton mounted on a roller'axle and pressed together to form a surface of relatively hard, unwoven structure which is deformable but not so elastic as to lose the pattern of embossing of the engraved pattern from the heated metal roll. The thermoplastic material, such as thermoplastic yarns, passes between the rolls and is crimped as the material is softened by the heated roll and so readily forms crimped structure which, on cooling, sets and provides a suitably texturized and/or bulked yarn.

Since the pattern of engraving, and therefore also of embossing, consists of slanted ridges slanting in a continuous direction, the tendency is for the rolls to move the surface of the embossed roll slightly axially. This has two undesirable results: In the first place, the surface of the embossed roll is no longer parallel to the roll surface of the engraved metal roll and hence scuffing or other imperfections in the crimped pattern of the yarns result. The second drawback is that wear on the embossed roll is accelerated and it has to be-trued off at fairly frequent intervals. This requires stopping the crimping machine and represents additional cost, both for labor and for loss of production, when the machine .is down for roller truing and re-embossing. Nevertheless, this has been considered a necessary evil or necessary price to pay for producing the crimped thermoplastic yarns which are used very extensively as they are texturized, bulked and produce desirable fabrics. It is with an improvement on the crimping rolls, and particularly the embossing roll, that the present invention deals.

SUMMARY OF THE INVENTION According to the present invention the heated metal roll is engraved with slanting lines going in different directions in different parts along the roll. This results in a roll pattern which is an inverted or upright V, and

of course also on the embossed roll, which is embossed by running it against the heated engraved roll with suitable moistening or other conditions which render the relatively hard, compressed, non-woven wool or wool fabric surface temporarily slightly softened so that it takes an embossed pattern which is the reverse of the engraved pattern on the heated metal roll. After embossing, the roll is cooled and dried, and its surface retains the embossed pattern for a much longer period of time than in the machines which were hitherto used because the slanting of the engraved pattern and embossed pattern does not cause the surface of the embossed roll to creep gradually in one direction, resulting in a non-uniform cross-section and rapid wear..The rolls, therefore, maintain pattern sharpness and alignment; scuffing and hence imperfectly crimped material is greatly reduced or eliminated, and it becomes necessary to true-up the surface of the embossed roll only at much longer intervals, which saves labor and loss of output during the time the machine is down.

In many machines the rolls are of moderate length and two inclined patterns are sufficient, in other words, the inclined engravings form a single inverted or a single upright V. For longer rolls they may be subdivided 0 into more portions axially, for example four. The embossed pattern on the embossed roll, of course, is likewise subdivided into the same number of areas. The exact angle at which the engravings slant, first in one direction and then in the other, is not critical and may vary from as little as 15 from the horizontal to as much as 60 or 70. The particular angle of slant is not what distinguishes the present invention from the prior art, and a very common angle of about 265, which is frequently used in crimping r'olls which have had their pattern slanting continuously in the same direction, may also be employed in the present invention and gives excellent results with decreased creep of the surface of the embossed roll.

It is also an advantage of the present invention that the methods of heating the heated roll, its drive and the like are not changed by the present invention, and these portions of standard machines may, therefore, be used with the improved rolls of the present invention. In general the temperature of the surface of the heated metal roll may be the same as used in the prior art, that is to say, for example, from 300 to 350F., depending somewhat on the nature of the thermoplastic yarn which is being crimped and hence its softening point.

The embossed roll, which is usually of considerably larger diameter than the heated engraved metal roll, can be made by essentially the same general procedure as was used for the embossed rolls in the past with the engraved rolls having the slant of engraving going in only a single direction. In general these rolls are made up on suitable axles or shafts by a series of rings of nonwoven, chopped wool and cotton which are then compressed under very high pressure and which may, if

desired, have a binder. There is, however, one difference which can be used and whichis an advantage of the present invention. Since the engraved roll has separated portions with engravings slanting in different directions, there will usually be a small gap between the engravings, and this gap may be opposite a strong section or washer on the embossed roll. Such a washer may be of metal and can increase quite markedly the resistance of. the shorter sections of the embossed roll to axial creep. In other words, in addition to the basic improvement of the present invention, which reduces creep by having the slanting of the engravings in different directions, the embossed roll may be additionally stiffenedThis is optional and not the most important single feature of the present invention. Of course if there are more than two zones on the roll with patterns slanting in different directions, there may be additional stiffeners'or stiffening spacers. For example, if the roll is divided into four zones, there would be three such spacers. It should be realized that these spacers are in addition to the strong metal end caps which are pressed under high pressure to compress the rings to form the roll. If we consider the metal caps as additional reinforcements or spacers, then the embossed roll would have one more such reinforcement than the number of zones rather than one less if we consider only the spacers between zones.

It is an advantage of the present invention that the improved rolls of the present invention may be used in machines of standard construction, which widens the field of utility of the present invention since it is not necessary to design whole new machines. Other operating conditions are also not necessarily changed except that sometimes the longer life of the surface of the embossed roll may permit somewhat higher operating speeds and, if desired, the engravings may be somewhat deeper, for the amount of creep on the surface of the embossed roll increases with depth of engraving and sometimes, therefore, the amount of crimping and hence bulking of the thermoplastic textile yarns may be practical with the improved rolls of the present invention without excessive creep of the surface of the embossed roll and/or excessively short life. The amplitude of the crimp in the thermoplastic yarn has an important effect on the bulking and texture of the yarn, and for certain uses a deeper engraving and hence greater amplitude of crimp is desirable. It is, therefore, an additional advantage of the present invention that where such greater amplitude of crimp is desired, the present inventionmakes such products practical. In no case are there any disadvantages in the rolls of the present invention, which, therefore, is not a compromise for which a price has to be paid in less desirable other characteristics.

The present invention is directed to the crimping rolls themselves. In the past there has been some problem with very brief contact of the crimped and softened yarns with the embossed roll, which may leave them insufficiently set as they are drawn off and result in a certain decrease in amplitude of'crimping. In my co-pending application Ser. No. 147,559, tiled May 27, 1971, l have described an improved crimping apparatus and process in which the first takeup roll for the crimped yarns after they have left the nip of the crimping rolls proper is lowered -to maintain the crimped ya'rn in contact with the embossed roll over a considerable angle of the periphery, for example from 75 to 145, When held against the crimping roll with its embossed patter mthe crimped yarns can cool off additional feature of my co-pending application. In

fact, the present invention makes it less necessary to support the crimped yarn for a considerable distance on the embossed roll because it is practical to crimp more deeply, i.e., a greater amplitude of crimp, and therefore, even if the crimp is slightly pulled out, the net result may be entirely satisfactory, whereas with the less deep engravings that were normally needed in the past in order to minimize embossed roll surface creep, the stretch may reduce amplitude of crimp below that desired. This is another advantage of the present invention because it makes possible in many cases an adequate final crimp amplitude without having to modify crimping machines by changing takeup roller position, which is necessary in the modifications covered by my co-pending application above referred to. Sometimes the savings in being able to use the improved rolls in an existing machine without any change in the machine whatsoever may be of sufficient importance so that the present invention can in such cases make it unnecessary or less necessary to 'use the process and construction of my co-pending application.

BRIEF DESCRIPTION OF THE DRAWINGS The drawings are an elevation of a pair of rollers according to the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the drawing the engraved heated metal roll is shown subdivided into two zones 1A and 1B with engraved patterns slanting in opposite directions, forming an inverted V. The slant illustrated is the common 26.5 which is used so frequently in engraved rolls in the past.

The mating embossed roll is also shown as divided into two zones 2A and 2B which receive an embossed pattern corresponding to that of the engraved roll in the zones 1A and 1B. The ring construction of the embossed roll is indicated by a plurality of rings 3, shown separated by lines on the drawing. The roll is also provided with'the customary metal caps 4 and, in addition, with a metal separator or washer 5 in the middle which is opposite the blank space 6 between the zones 1A and 1B in the engraved roll. There are three blank spaces 6 on the engraved roll and the blank space 6 which is opposite the metal washer 5 on the embossed roll is the center one, as described. At the ends of the embossed roll there are twosmooth spaces which are opposite the outer blank spaces 6 on the engraved roll and are,-

therefore, not embossed. This central blank space is shown somewhat exaggerated in width for the sake of clarity. In order to show the rings 3 on the embossed roll, the slanted embossed grooves formed by the engraved roll are shown only in some small areas. Of course these embossings extend over the full surface of the sections 2A and 2B of the embossed roll. I

As the drives for the rolls are not changed by the present invention, nor is the heating means for the engraved metal roller, which may be a conduit introducing steam axially or any other heating means, they are not shown in order not to confuse the drawings. The shape of the crimps are, of course, the same as inthe past except that the slant of the engraved patterns are different in zones 1A and 18. For the same reason takeup and outfeed rolls are not shown in the drawing asrthey would only confuse the illustration and their location and operation are not changed by thepresent invention.

In the operation of the rolls shown in the drawing the heated engraved roll is maintained at the same temperatures as are customary in the prior art, for example from 300F. to 350F. The other features of normal operation are not changed except that, as has been mentioned above, somewhat deeper engravings may be used and in some cases the rate at which the thermoplastic yarns pass through may be increased.

I claim:

1. In a crimping apparatus for crimping thermoplastic textile material which comprises two rolls, one engraved metal roll which is heated mating with a non-elastic embossed roll having a rigid firm nonwoven surface of fibrous material, the improvement which comprises at least one pair of slanted engraved patterns in the engraved roll, adjacent patterns slanting in opposite directions and forming Vs, the slants varying from about to the horizontal to 60, with the patterns embossed on the embossed roll having corresponding orientations, whereby creep of the surface of the embossed roll in a single direction and nonuniform cross-sections of the embossed roll are minimized, resulting in a reduction of scuffing and frequency of truing of the embossed roll.

2. An apparatus according to claim 1 in which the number of zones of engraving at different angles is two.

3. An apparatus according to claim 1 in which the embossed roll consists of a series of rings of fibrous material on a central shaft, said rings being highly compressed between rigid caps, the rings being of uniform diameter, non-elastic, and having a peripheral surface which is rigid and firm and provided with embossed patterns mating with the patterns on the heated, engraved metal roll.

4. An apparatus according to claim 1 in which there is a narrow gap between the patterns engraved on the engraved roll and opposite this narrow gap is a rigid stiffening washer in the embossed roll.

5. An apparatus according to claim 4- in which the number of zones of engraving at different angles is two.

6. An apparatus according to claim 1 in which the embossed roll consists of a series of rings of fibrous material on a central shaft, said rings being highly compressed between rigid caps, the rings being of uniform diameter, non-elastic, and having a peripheral surface which is rigid and firm and provided with embossed patterns mating with the patterns on the heated, engraved metal roll.

Patent No. 3,714,685 ated February 1- 73 Harold Dean Yarber Inventor(s) It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

I I Claim 6, line 1; "claim 1" should read c1aim-2 Signed and sealed this 20th day of August 1974.

(SEAL) Attest:

Mc COY M. GIBSON; JR. C. MARSHALL DANN I Attesting Officer Commissioner of Patents oRM Po-wso (10-69) USCOMM-DC 60376-P69 U.S GOVERNMENT PRINTING OFFICE: IS, 0-;66-33. 

1. In a crimping apparatus for crimping thermoplastic textile material which comprises two rolls, one engraved metal roll which is heated mating with a non-elastic embossed roll having a rigid firm non-woven surface of fibrous material, the improvement which comprises at least one pair of slanted engraved patterns in the engraved roll, adjacent patterns slanting in opposite directions and forming V''s, the slants varying from about 15* to the horizontal to 60*, with the patterns embossed on the embossed roll having corresponding orientations, whereby creep of the surface of the embossed roll in a single direction and nonuniform cross-sections of the embossed roll are minimized, resulting in a reduction of scuffing and frequency of truing of the embossed roll.
 1. In a crimping apparatus for crimping thermoplastic textile material which comprises two rolls, one engraved metal roll which is heated mating with a non-elastic embossed roll having a rigid firm non-woven surface of fibrous material, the improvement which comprises at least one pair of slanted engraved patterns in the engraved roll, adjacent patterns slanting in opposite directions and forming V''s, the slants varying from about 15* to the horizontal to 60*, with the patterns embossed on the embossed roll having corresponding orientations, whereby creep of the surface of the embossed roll in a single direction and non-uniform cross-sections of the embossed roll are minimized, resulting in a reduction of scuffing and frequency of truing of the embossed roll.
 2. An apparatus according to claim 1 in which the number of zones of engraving at different angles is two.
 3. An apparatus according to claim 1 in which the embossed roll consists of a series of rings of fibrous material on a central shaft, said rings being highly compressed between rigid caps, the rings being of uniform diameter, non-elastic, and having a peripheral surface which is rigid and firm and provided with embosSed patterns mating with the patterns on the heated, engraved metal roll.
 4. An apparatus according to claim 1 in which there is a narrow gap between the patterns engraved on the engraved roll and opposite this narrow gap is a rigid stiffening washer in the embossed roll.
 5. An apparatus according to claim 4 in which the number of zones of engraving at different angles is two. 